Centrifugal basket



April 13,1926. 1,581,089

E. ROBERTS CENTRIFUGAL BASKET Filed June 30; 1923 5 Sheets -Sheet 1 COOJ m A. Q Mom MGM wow wow c o 2 M u 1 o o o o v n o o o o o o o o -m m0M0 own 0M0 owe a o 0 0 0 o \o o o 0/ i I /Z\\ A ril 13,1926; 1,581,089

E. ROB ERTS CENTRIFUGAL BASKET Filed June 50, 1923 1 5 Sheets- Sheet 2WM MW) K April 13 1926.

E. ROBERTS CENTRIFUGAL BASKET Filed June 50 192-3 5 sheets sheet .5

A r ii1a, 192e.' 1,581,089

E. ROBERTS GENTRIFUGAL BASKET Filed June 30, 1923 5 Sheets-sheet 4 April13 1926. 1,581,089

E. ROBERTS CENTRIFUGAL BASKET Filed June 30, 1923 5 Sheets- Sheet 5Patented Apr. 13, 1926.

UNITED STATES PATENT OFFICE.

EUGENE ROBERTS, OF SALT LAKE CITY, UTAH, ASSIGNOR TO THE WESTERN STATESMACHINE COMPANY, OF SALT LAKE CITY, UTAH, A CORPORATION OF UTAH;

CENTRIFUGAL BASKETS Application filed June so, 1923. Serial No. 648,676.

T aZZ whom it may concern:

Be it known that I, EUGENE Ronnn'rs, a citizen of the United States, andresident of Salt Lake City, in the county of Salt Lake and State-ofUtah, have invented certain new and useful Improvements in CentrifugalBaskets, of which the following is a specification.

In the manufacture or refining of sugar or like materials by centrifugalseparation of the liquid content, whether syrup or wash liquid, from thesolid content or grains, much difficulty has been experienced inproviding means for effectively retaining in the centrifugal basket thesolid grains or crystals while permitting the rapid escape of the liquidcontent through the basket wall. Heretofore it has been the practice topunchor drill discharge holes of inch or 2 less diameter through thebasket wall with centers an inch or more apart. Against the inside faceof such perforated basket wall was placed the filter elements comprisinga very finely and closely perforated screen of thin sheet brass or thelike with a backing of wire mesh. 3 The great outward pressure of .thesolid sugar against the screen due to centrifugal force tended toflatten the wire mesh against the inside wall of the basket so thattherewas practically little or no drainage of the liquid over thegreater portion of the imperforate areas of the basket between thebasket wall perforations. As .the perforations occupied only a smallperthe process of effecting the desired separation of the-liquid juicefrom the solid grains of sugar or other material was unduly prolonged,thus wastingtime and thereby recentage of the total area of the'basketwall ducing the output of each machine, while the washing operation wasnot only unduly to resist the powerful outward the sugar and yet allowthe liquids to flowfreely into the drainage passages without screenunder the pressure of the sugar to press the wire mesh backing into suchholes and thus injureboth lining and screen and cause them to smear withsugar whenever such backing or stretching occurred.

The present invention overcomes these difficulties by providing a filterconstruction for the basket wall so arranged and dimensioned as toafford practically complete drainage for the entire area of thesugarsustaining basket Wall instead of affording dralnage merely foronly a. small portion of said area as hereto-fore, thereby materiallyaabbreviating both the duration of the juiceseparating operation andthat of the washing operation besides decreasing materially the quantityof water required and the consequent waste of sugar carried ofi'normally closed .aga-inst'percolation of the liquid by reason of thefact that the attach.-

ing ring, the sub-tending part of the basket and the outer reenforeingband form a solid annular'wall preventing any effective drainage so thatthe opposed section of the sugar wall 'is very imperfectly treated bothas to extraction of the juice and as to washing of the sugar grains. 4

According to the present invention -1 overcome this difiiculty'by\providing this attaching rim or flange of the basket bottom this typeof machine, with adequate drainage passages which are covered by asieve-like screen or stralner so sup 'rted as rust of materialobstruction. j s

For the first time in the history of-the art this invention provides afilter construction for a centrifugal basket in which the entiresugar-sustaining area of the-basket wall is the basket wa l itself.

effectively drained without'leaving considerable areas practicallydevoid of drainage facilities. x Y

These and other features of the mve tion will be particularly describedin the following specification and will be defined in the claims heretoannexed.

In the accompanying drawin illustrated some of the forms W trate theprinciples and vention, in which:

Figure 1 is an elevation of a centrifugal basket as ordinarily suspendedfor'use, the wall being partly broken away to show the interiordeflector.

Fi re 2 is a plan view of the same, part of the top of the basket beingbroken away.- Figure 3 is a centrifugal. section through one side of thebasket illustrating the arrangement and construction of filter elements.7 i J Figure 4 is a similar section showing the the wall-sppporting rims I have ich illus basket adjacent to of the basket bottom on a largerscae.

Figure 5 is an isometric elevation of a portion of the basket wall asviewed from the interior illustrating the progressive building up of thedifferent layers or elementsof the filtering wall.

Figure 6 is a sideelevation partly in section of the assemblage shown inFigure 5. Figure 7 is a similar view showing a part of the grid, orocket-ferming element of the filtering wall Figure 8 is a face view asseen from the inside of the bridge plate which forms a support for thefiltering elements over'the shallow pockets.

Figures 9 and 10, show, respectivel in elevationand in crosssection a moified the basket wall in which form of a portion of grid is integralwith the filter-sup orting Figures 11, 12 and 13 are sectional viewsthrough the basket wall' adjacent to the overlapped joint of the bottomand side wall illustrating modified constructions for draining thisarea.

tom ty cable toprotecting conical bottom and Figure 14 is a horizontalsection through a short length of'the basket wall adjacentto one of thejoints betweensthe sections.

Since a similarly constructed filter wall for covering the perforationsin the peri'ph-' eral or cylindrical wall of'the basket may be equally'well used for the fiat valved bottom se f-discharging basket, in theaccofnhave'illustrated the cons latter type of-ba'sket because ofcertain additional features that are peculiarly applithe" joint betweenthe the cylindrical wall of a self-discharging basket. j

The perforated. basket, therefore, embraca central spider 8 practice ofthis in tion 12 may be properly drained placing against by means of asomewhat e of basket and for the ta'gered bot-,-

ing the cylindrical wall 1, the sloping top ring 7, and the conical baseorlbottom 9, formed with an upper attaching ring or flange 9 and a lowerattaching flange 9", is suspended in the usual manner by means of whoseperipheral band 8" fits inside the lower flanged end of the conicalbottom on the rotary basket shaft 2, which is coupled to the upperrotary shaft section 5, carried by thegyratory suspender 3 on a ball andsocket joint at 4, by means-of hung a flanged connection shown at 6,according to present well known practice, in order that the basket mayrotate and gyratein use.

' Both the cylidrical wall 1, and the hot I tom wall 9 are provided withliquid discharge openin s 12 whose inner edges are preferably slightlyflared or countersunk as shown at 15 in order to more readily collectthe liquid that percolates through the filtering material into theshallow collecting pockets, hereinafter mentioned, surrounding eachdischarge perforation. I

In order that the imperforate parts of the basket surrounding eachdischar e perforathe basket walls with shallow drainage pockets on itsinterior face, 'referably by said interior ace a grid 20 I provideconsisting usually of sheet metal with the major part of the sheet cutout to form windows or openings arranged to surroundeach perforation 12but of considerably larger area than such erforations, these pocketsbeing bounded y relatively narrow ribs forming the grid as best shown inFigure 5.

, Such grid is placed inside the basket and is preferably riveted brotherwise secured thereto at suitable. intervals, the abutting ends beinbrought together but not overlapping, his construction, therefore,rovides a .series of shallow drainage poc etc on the interior face-ofthe basket wall of much larger area than it would be practicable to makethe perforations themselves and of much larger area, than the solid ribsor arts of the grid that bound the pockets.

he preferred construction for the filtering elements comprlses a finelyand closely perforated sheet metal screen or sieve 23 backed by asomewhat coarser wire mesh fabric 22 which itself is "supported againstbuckling into the shallow plockets or recesses eavier and more coarselyperforated bridge plate 21, as shown in enlarged view in Figure 4. Thesethree-elements may conveniently be riveted together and preferably,instead of making them in one continuous ring to fit inside the basketwall, they are made in any desired number of sections div'idedvertically with the screen or sieve portion 23 continued slightly beyondthe abutting joint of the sections to overlap and protect the verticalUsually the basket rotates in a clockwise direction, and in such casethe overlap of the screen cross joint would be thatindicated'in Figure14, the rear edge of each section overlapping the forward edge of eachfollowing section considered with regard to the directlon of rotation ofthe basket.

/With the sectional arrangement described it will usually be foundadvantageous to rivet the coarsely perforated brid e or supporting plate21 and the two filtering layers 22, 23, together as illustrated at 25 inFigure 4. Any suitable means may be employed for retaining the interiorcomposite filtering wall in position, butin the present instance I haveshown such filtering wall held in place by the outer adjacent edge ofthe top filtering element 26 and of the lower filtering element whichslightly overlap the top and bottom eaves respectively of the compositefiltering element, as illustrated in Figure 3, but in this case withouttightly binding against the filtering element since a slight creep ofthe latter relative to the basket wall is not necessarily injurious.

The ring of sugar building up against the underside of the top ring orrim 7 of the basket should be completely drained to obtain the mosteffective results and, therefore, I provide an annular compositefiltering element comprising the coarsely perforated plate 26 similar toplate 21 which is covered on the side toward the sugar wall withacorresponding plate or strip 27 of finely perforated screen, similar tothe screen '23, which is preferably riveted to the supporting plate26.In order' to space this top filtering wall from the solid face of therin I provide a series of narrow radial ribs 7 on the undersideof thering 7 so as tofo rm shallow radial passages for the flow of theextracted liquid outwardly to the adjacent discharge openings 12.

To'effectfull and complete drainage of the filtering wall covering thefrustno-conical bottom of the basket I provide the inner ,face of theinclined bottom wall 9 with a series ofshallow. supporting ribs 13,which, in this instance althoughnot necessarily, ex tend around theinside ofthe bottom at properly spaced intervals in a circumferentialdirection in order to form shallow drainage pockets 14. The uppermost ofthese drainage pockets as most clearly shown Figure 4, extends welltoward the top of H the connecting-ring or flange 10 and at its upperedge communicates at intervals through drainage passages 10 with theperforations 12. formed in the outer wall of the basket. All-thesedrainage passages in the bottom are covered by means of a relativelyheavybridge plate or screen-supporting element 30 on the inside of whichis mounted a finely perforated screen orsieve g 12 in the basket wall 1.

31, similar to screen 23. As shown in Figures 3 and 4, the upper edge ofthe filtering screen 31 projects slightly beyond the edge,

form a slight overlap. Attaching screws 33 .ofits supporting plate, asshown at 32 to} or equivalent means are passed at intervals through thescreen wall 30, 31, into the ribs 13 to hold the filtering wall inplace, and as an additional means of resisting the upward thrust due tocentrifugal force annular ribs 34 are fastened to the outer face of theplate 30 in position to engage the lower side of the spacing ribs 13 andthusrelieve the pressure on the attaching screws.-

From the foregoing description and an inspection of the detailedconstruction and arrangement illustrated in Figure 3 it will be seenthat there is no part of the finely perforated filtering screen that isnot in communication with outlet or drainagepassages and that,consequently every smallest portion of the wall of sugar or other solidis subjected to the most'complete drainage ac tion since there is nosolid wall preventing the flow of liquid to the basket wall dischargeoutlets under the action of centrifugal force. \Vith all parts of thesugar wall fully drained very rapid and effective separation of theliquid syrup or wash water is accomplished without producing substantialareas of-imperfectly washed material.

In Figures 9 and 10 I have shown a slightly modified form inwhich thepocketforming grid 20 corresponding to the pocket-forming grid 20, abovedescribed, is formed integrally with the basket wall by countersinkingshallow pockets 20 which communicate with the discharge openings As willbe seen these circular pockets 20 cover much the greater portion of theinside face of the basket wall and function precisely as do the pocketsformed by the separate grid 20.

In Figure 11 I have shown in vertical cross section a modified form ofconstruction in which a. separate detachable ring 35 is inserted abovethe attaching ring 10 to form a supporting ledge upon which the bottomedge of the composite filtering wall rests, and also a downwardly turnedledge 35 to support the upward thrust of the filtering wall 30, 31,which latter is similar to that already described for theconical bottom9. In this case tbs; inclined inner face of the screen-supporting ring35 is protected by means of an annulan bridge plate 36 made incircumferential sections and covered with the finely perforated screen37. This protecting screen is held in spaced relationship to the insidewall of the ring 35 by means of attaching screws 38 and. vhas its upperand lower edges bevelled to overlap and bear element. The liquiddischarges into the 37, similar to that above described rests uponnarrow annular ribs 35 and 35 instead ofgetting its outward bearingagainst the cylindrical filtering element and the conical filteringelement, as in the form shown in Figure 11.

In the form shown in Figure 13, the retaining ring 40, is provided withan upper screen-retaining flange 41 and a lower screenretaining flange42, and is provided with vertical ribs 43 to support the filtering-plate36 at frequent intervals. It will, therefore, be seen that where such ascreen-supporting ring is used in the centrifugal basket provision maybe made in various ways, inaccordance with the principle of thisinvention, to prevent smearing of the .sugar against the ring byproviding ample drainage passages for the inside surface of the ring incommunication with the sieve-like perforations of the screen and withthe outlet ierforations of the basket wall.

The perforations in the filter-supporting or bridge plates areinadelarge enough to cover a number ofinterstitial spaces in the wiremesh layer and are arranged as closely as practicable without makin thebridge plate too weak to prevent bulging of the filtering element intothe'large shallow drainage recesses which they eover. The wire:

mesh is coarse enough to enable each interstitial space to subtendseveral of the fine perforations in the screen while the round wires andundulating surface of the wire mesh allow suflicient lateral circulationfor the very short distance involved to give perfect drainage betweenthe screen perforating and the discharge holes in the basket. Thepunching out of the grid and of the bridge plate tends to somewhatindent or round the edges surrounding the openings so that there isnowhere presented throughout the whole sugar subtended wall anysubstantial impediment to the rapid escape of liquid through the basketwall. Thus full drainage is provided for every portion. of the walled upmaterial, and all the screen perforations are in communication with thedischarge holes in the basket wall.

This will be clear if we consider that the solid strips forming thespacing grid need of the liquid to the discharge holeso basket wall.Furthermore,.as the interstices the conical bottom screen and betweensaid screen and said vided with closely arran 'ed re atively coarseperforations affording. ree communication not ekizeed th inch in width,and as the perforations in the bridge plate-maybe of 5th inch diametereven the solid parts of the grid form no obstacle to the circulppion'the of the wire mesh may be as wide or widen than the width of thesolid portions of the bridge plate, and as the wires of the mesh, evenwhen directly opposed to a row of fine perforations of the screen, stillleave room for the escape of liquid through the fine perforations thepercolation of the liquid, under centrifugal force, from everyperforation in the strainer screen is permitted. Hence it is thatcomplete drainage is afiorded to every part of the walled-u materialwith resulting absence of any dar 'zones or areas of syrup-bearing orunwashed sugar and this, too, with the use of a less volume of washwater and with a material shortening of the cycle o-f'centrifugaloperations.

Intermediate of the top and bottom annular walls ofthe'basket I providea circular deflector plate 50 secured to the basket shaft 2, and havingon its upper face radiating ribs or flanges 51, which are bent backrelative to the direction of rotation of the basket in order to' retardthe centrifugal action from throwing off the fed-in material to the wallof the basket while accelerating the rotary motion of the materialbefore it impinges against the surrounding basket wall.

What I claim is:

1. A filterin construction for a centrifugal basket em racing incombination with a surrounding basket wall formed ,with dischargeperforations well spaced apart, an interiorly disposed fine foraminousfilter screen, an intermediately dis osed relatively stiff bridge platehaving 0 osely arranged coarse perforations while providing "substantially level support at intervals to sustain the screen against Ioutwardbulging under pressure, and spacing means afi'ording at intervalsexterior supportin engagement with the bridge plate to form-drainagespaces on the interior of the basket wall directly tributarl todischarge perforations in the basket wa 2. A filterin construction for acentrifu-' gal basket em racing in combination with the surroundingperforated basket wall, a

grid member whose openings occupy the drainage pockets directlytributary to the ion liquid discharge perforations of the basket wall, afine foraminous filter screen support ed against bulging into saidockets under the outward thrust of the has et load by a relatively stiffbridge plate being interposed id and probetween the filter perforationsand said drainage pockets whereby the rapid escape of the centrifugallyextracted liquid is facilitated, substantially as described.

S. A filtering construction for a centrifugal basket embracing incombination with filterserecn, and a supporting grid interposed betweenthe basket wall and the bridge-plate to separate the bridge-plate fromcontact with the basket well, said grid having openings of substantiallylarger area than the area of the basket Wall perforations formingdrainage pockets around the basket wall perforations, substantially asdescribed.

' 4. A filtering construction fora centrifugal basket embracing incombination with a perforated basket wall, a spacing element arrangedagainst the inside of the basket and provided with openlngs ofsubstantially larger area than the basket wall perforations therebyforming shallow drainage pockets around the basket wall perforations, afine foraminous filter screen arranged interiorly of the spacing elementto allow the escape of centrifugally extracted liqmd while retaining thesolid contents of the basket, and means interposed between the spacingelement and the-filter screen to support the filter screen againstbulging into said pockets while allowingthe extracted liquid to flowfreely thereto, substantially as dey scribed.

face of the basket to leave shallow drain-- age pockets of larger areathan the area of the perforations in the basket wall, a relatively latearranged to bridge over said pockets, a finely perforated sheet metalfilter screen, arranged inside said bridge plate and a reticulatedbacking, interposed T between the bridge plate and the screen,substantially as described. I

6. A filter construction "for a centrifugal basket, embracing incombination with a perforated thrust-sustaining basket wall, a thinfinely perforated metallic filter screen, a relatively stiff bridgeplate having relatively coarse closely arranged perforations for theescape 'of' the liquid extracted through said screen, said bridge plateaffording firm support for the screen to pre vent the screen frombulging out under internal pressure, and spacing means arranged therebyaffording free drainage outlets for stiff closely-perforated bridge toseparate the bridge-plate from the subtending portions of the basketwalland form drainage pockets communicating with liquid discharge openingsin the basket wall,

all parts ofthe screen, substantially as described.

7. A filter construction for a centrifugal basket embracing incon'ibination with the perforated basket wall, spacing-means on itsinner face arranged'to form shallow drainag pockets of larger area thanthat of the bar; et wall perforations, segmental filtering elements eachcomprising a relatively stiff coarsely perforated bridge plate ofsegmental form, and a thin, sheet metal finely perforated screen ofsimilar form firmly so cured to said segmental bridge plate, substantially as described. v

' 8. A filtering element for acentrifugal basket embracing a relativelystiff coarselyperforated bridge plate of segmental form and a finelyperforated thin sheet metal filter screen of like form riveted theretowith one side edge extending slightly beyond the corresponding side edgeof the bridge plate to overlap the edge of the next adjacent elementwhen assembled in the basket, substantially as described.

9. A bottom for a centrifugal basket embracing a funnel shapedperforated mem her having upper and lower attaching flanges forconnection respectively witha peripheral basket andwith an interiorsupporting spider, interiorly projecting ledges forming drainagepassages leading to liquid discharge openings, arigid'closely-perforated frustro-conical bridge member inf teriorlysupported upon said ledges, and a, frustro-conical filter screen offinely perforated thin metal supported on said bridge plate againstoutward bulging under pressure, substantially as describe i 10, A.filtering construction for a selfdischarging centrifugal basketembracing in combination with a perforated peripheral side wall, adownwardly converging perforated conical bottom whose upper edge portion forms an attaching ring in overlapped relation. to the loweredgeportion of said side wall, filtering elements arranged to coverrespectively the perforations of the side wall and of the bottom, thebottom filterelement embracing a finely perforated filter screenextending-over the inside of the overlapped attaching ring with itsperforations subtending said ring draining .into liquid dischargeopeningsin the'basket, substantially as described.

11. A filtering construction fora self discharging centrifugal basketembracing in combination a perforated side wall, a downwardly convergingconical bottom secured to the lower ed e of the sidewall by-anoverlapped attac ing rim portioma filterlac ing element e'mbra'cing athin finely perforated filter screen'formmg an inside cover for shallowdrainage pockets surrounding the perforations in the side wall of thebasket, and means for supporting said screen against bulging into saidpockets while allowing extracted liquid to pass thereto, a

similar filtering element arranged inside the conical bottom to coverdrainage areas leading to liquid discharge perforations, thelatter'fi'ltering element extending upward to cover liquid dischargepassages in the over- .lapped rim portion of the bottom, substantiallyas described. 1

p 12. A self-discharging centrifugal basket embracing a perforated sideWall and a downwardly converging perforated conical bottom securedtogether with their adjaage to the perforations therein the filteringscreen of the bottom being extended up to overlap the lower edge of thefiltering element of the side wall, there being pro vided liquiddischarge passages to drain the screen perforations subtending theoverlapped" portions of the side wall and the bottom. i

13. A filtering element for the. conical bottom of a self-dischargingcentifugal basket embracing a segmental frustro-conical screen of thinfinely perforated material, a, bridge member of similar shape to whichthe screen is secured, and means carried by the bridge plate to engageledges in the bottomof the basket 'to prevent upward shifting of thefiltering element under the stress of centrifugal force, substantiallyas described.

In witness whereofiIhav'e subscribed the above specification.

a EUGENE ROBERTS.

